Hydrodynamic forces on a rotating sphere

Abstract

The wake dynamics of a rotating sphere with prescribed rotation axis angles are quantitatively analysed by carrying out numerical simulations at Reynolds numbers of Re=100, 250 and 300, non-dimensional rotational rates Ω*=0-1 and rotation axis angles α=0, π/6, π/3 and π/2 measured from the free stream axis. These parameters are the same as those in an earlier study (Poon et al., 2010, Int. J. Heat Fluid Flow) where the instantaneous flow structures were discussed qualitatively. This study extends the findings of the earlier study by employing phase diagrams (CLx,CLy) and (CD,CL) to provide a quantitative analysis of the time-dependent behaviour of the flow structures. At Re=300 and Ω*=0.05, ..